C# - how do I prevent mousewheel-scrolling in my c

问题:

I have a combobox and I want to prevent the user from scrolling through the items with the mousewheel.

Is there an easy way to do that?

(C#, VS2008)

回答1:

Use the MouseWheel event for your ComboBox:

void comboBox1_MouseWheel(object sender, MouseEventArgs e) {
    ((HandledMouseEventArgs)e).Handled = true;
}

Note: you'll have to create event in code:

comboBox1.MouseWheel += new MouseEventHandler(comboBox1_MouseWheel);

回答2:

For WPF, handle the PreviewMouseWheel event instead.

It would also be a good idea to consider ComboBox.IsDropDownOpen so the user can still use mouse scroll if there are a lot of items in the selection when the ComboBox is expanded.

Another thing is to apply the same behavior across the whole application.

I usually do all the above using the following code:

App.xaml

<Application.Resources>
    <Style TargetType="ComboBox">
        <EventSetter Event="PreviewMouseWheel" Handler="ComboBox_PreviewMouseWheel" />
    </Style>
</Application.Resources>

App.xaml.cs

private void ComboBox_PreviewMouseWheel(object sender, System.Windows.Input.MouseWheelEventArgs e)
{
    e.Handled = !((System.Windows.Controls.ComboBox)sender).IsDropDownOpen;
}

回答3:

I use another solution that also works on Mono.

Goal is to prevent accidentally scrolling (that is when the user is not looking at the comboBox when using the mouse wheel). If he / she scroll outside the visible portion of comboBox , the combo box should not scroll, otherwise it should.

My solution:

• Place a read only text box outside the visible portion of the screen. In form_load I placed the line: hiddenTextbox.left = -100 ;

• Set the focus to this text box when the mouse leaves the combo box using mouse leave event. In comboBox1_MouseLeave I placed the line: hiddenTextbox.focus();

• Handle mouseWheel event: From1.MouseWheel += Form1_MouseWheel; textBoxHidden.MouseWheel += Form1_MouseWheel;